Intrinsic Josephson Tunneling in High-Temperature Superconductors

Intrinsic Josephson tunneling takes place between copper-oxide (CuO) planes of several anisotropic high-temperature superconductors, such as Bi

2

Sr

2

Ca Cu

2

O

8 + δ

(Bi2212). To study the intrinsic tunneling effects, mesas are usually patterned into the surfaces of Bi2212 single crystals. The mesa structure contains an array of typically 5–30 intrinsic Josephson junctions formed between adjacent superconducting CuO planes. The number of defects that could affect measurements is limited in the small volume of the mesa. Variations in the carrier concentration and introduction of columnar defects by heavy-ion irradiation can be used to control the correlations and pinning of magnetic vortex pancakes. The intrinsic tunneling provides information on the magnetic phase diagram of Abrikosov vortices, allows for direct measurements of the superconducting critical current of the individual CuO planes, permits for the observation of macroscopic quantum tunneling, allows for tunneling spectroscopy of phonons, the superconducting- and pseudo gaps, and shows coherent THz radiation of significant power.